Washed suspensions of Escherichia coli were exposed to different concentrations of Chlorine Dioxide at various temperatures. Platings of the mixtures to evaluate the numbers of surviving cells were made after 5–300 sec of contact. Survival data were best fitted by a reaction model that is first order with respect to cell concentration and to exposure time. Bactericidal rates were found to increase markedly with both increased Disinfectant concentrations and increased temperatures. Activation energies at each concentration of chlorine dioxide are reported.